block/nfs.c

   1 /*
   2  * QEMU Block driver for native access to files on NFS shares
   3  *
   4  * Copyright (c) 2014 Peter Lieven <pl@kamp.de>
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "config-host.h"
  26
  27 #include <poll.h>
  28 #include "qemu-common.h"
  29 #include "qemu/config-file.h"
  30 #include "qemu/error-report.h"
  31 #include "block/block_int.h"
  32 #include "trace.h"
  33 #include "qemu/iov.h"
  34 #include "qemu/uri.h"
  35 #include "sysemu/sysemu.h"
  36 #include <nfsc/libnfs.h>
  37
  38 #define QEMU_NFS_MAX_READAHEAD_SIZE 1048576
  39
  40 typedef struct NFSClient {
  41     struct nfs_context *context;
  42     struct nfsfh *fh;
  43     int events;
  44     bool has_zero_init;
  45     AioContext *aio_context;
  46     blkcnt_t st_blocks;
  47 } NFSClient;
  48
  49 typedef struct NFSRPC {
  50     int ret;
  51     int complete;
  52     QEMUIOVector *iov;
  53     struct stat *st;
  54     Coroutine *co;
  55     QEMUBH *bh;
  56     NFSClient *client;
  57 } NFSRPC;
  58
  59 static void nfs_process_read(void *arg);
  60 static void nfs_process_write(void *arg);
  61
  62 static void nfs_set_events(NFSClient *client)
  63 {
  64     int ev = nfs_which_events(client->context);
  65     if (ev != client->events) {
  66         aio_set_fd_handler(client->aio_context,
  67                            nfs_get_fd(client->context),
  68                            (ev & POLLIN) ? nfs_process_read : NULL,
  69                            (ev & POLLOUT) ? nfs_process_write : NULL,
  70                            client);
  71
  72     }
  73     client->events = ev;
  74 }
  75
  76 static void nfs_process_read(void *arg)
  77 {
  78     NFSClient *client = arg;
  79     nfs_service(client->context, POLLIN);
  80     nfs_set_events(client);
  81 }
  82
  83 static void nfs_process_write(void *arg)
  84 {
  85     NFSClient *client = arg;
  86     nfs_service(client->context, POLLOUT);
  87     nfs_set_events(client);
  88 }
  89
  90 static void nfs_co_init_task(NFSClient *client, NFSRPC *task)
  91 {
  92     *task = (NFSRPC) {
  93         .co             = qemu_coroutine_self(),
  94         .client         = client,
  95     };
  96 }
  97
  98 static void nfs_co_generic_bh_cb(void *opaque)
  99 {
 100     NFSRPC *task = opaque;
 101     task->complete = 1;
 102     qemu_bh_delete(task->bh);
 103     qemu_coroutine_enter(task->co, NULL);
 104 }
 105
 106 static void
 107 nfs_co_generic_cb(int ret, struct nfs_context *nfs, void *data,
 108                   void *private_data)
 109 {
 110     NFSRPC *task = private_data;
 111     task->ret = ret;
 112     if (task->ret > 0 && task->iov) {
 113         if (task->ret <= task->iov->size) {
 114             qemu_iovec_from_buf(task->iov, 0, data, task->ret);
 115         } else {
 116             task->ret = -EIO;
 117         }
 118     }
 119     if (task->ret == 0 && task->st) {
 120         memcpy(task->st, data, sizeof(struct stat));
 121     }
 122     if (task->ret < 0) {
 123         error_report("NFS Error: %s", nfs_get_error(nfs));
 124     }
 125     if (task->co) {
 126         task->bh = aio_bh_new(task->client->aio_context,
 127                               nfs_co_generic_bh_cb, task);
 128         qemu_bh_schedule(task->bh);
 129     } else {
 130         task->complete = 1;
 131     }
 132 }
 133
 134 static int coroutine_fn nfs_co_readv(BlockDriverState *bs,
 135                                      int64_t sector_num, int nb_sectors,
 136                                      QEMUIOVector *iov)
 137 {
 138     NFSClient *client = bs->opaque;
 139     NFSRPC task;
 140
 141     nfs_co_init_task(client, &task);
 142     task.iov = iov;
 143
 144     if (nfs_pread_async(client->context, client->fh,
 145                         sector_num * BDRV_SECTOR_SIZE,
 146                         nb_sectors * BDRV_SECTOR_SIZE,
 147                         nfs_co_generic_cb, &task) != 0) {
 148         return -ENOMEM;
 149     }
 150
 151     while (!task.complete) {
 152         nfs_set_events(client);
 153         qemu_coroutine_yield();
 154     }
 155
 156     if (task.ret < 0) {
 157         return task.ret;
 158     }
 159
 160     /* zero pad short reads */
 161     if (task.ret < iov->size) {
 162         qemu_iovec_memset(iov, task.ret, 0, iov->size - task.ret);
 163     }
 164
 165     return 0;
 166 }
 167
 168 static int coroutine_fn nfs_co_writev(BlockDriverState *bs,
 169                                         int64_t sector_num, int nb_sectors,
 170                                         QEMUIOVector *iov)
 171 {
 172     NFSClient *client = bs->opaque;
 173     NFSRPC task;
 174     char *buf = NULL;
 175
 176     nfs_co_init_task(client, &task);
 177
 178     buf = g_try_malloc(nb_sectors * BDRV_SECTOR_SIZE);
 179     if (nb_sectors && buf == NULL) {
 180         return -ENOMEM;
 181     }
 182
 183     qemu_iovec_to_buf(iov, 0, buf, nb_sectors * BDRV_SECTOR_SIZE);
 184
 185     if (nfs_pwrite_async(client->context, client->fh,
 186                          sector_num * BDRV_SECTOR_SIZE,
 187                          nb_sectors * BDRV_SECTOR_SIZE,
 188                          buf, nfs_co_generic_cb, &task) != 0) {
 189         g_free(buf);
 190         return -ENOMEM;
 191     }
 192
 193     while (!task.complete) {
 194         nfs_set_events(client);
 195         qemu_coroutine_yield();
 196     }
 197
 198     g_free(buf);
 199
 200     if (task.ret != nb_sectors * BDRV_SECTOR_SIZE) {
 201         return task.ret < 0 ? task.ret : -EIO;
 202     }
 203
 204     return 0;
 205 }
 206
 207 static int coroutine_fn nfs_co_flush(BlockDriverState *bs)
 208 {
 209     NFSClient *client = bs->opaque;
 210     NFSRPC task;
 211
 212     nfs_co_init_task(client, &task);
 213
 214     if (nfs_fsync_async(client->context, client->fh, nfs_co_generic_cb,
 215                         &task) != 0) {
 216         return -ENOMEM;
 217     }
 218
 219     while (!task.complete) {
 220         nfs_set_events(client);
 221         qemu_coroutine_yield();
 222     }
 223
 224     return task.ret;
 225 }
 226
 227 /* TODO Convert to fine grained options */
 228 static QemuOptsList runtime_opts = {
 229     .name = "nfs",
 230     .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
 231     .desc = {
 232         {
 233             .name = "filename",
 234             .type = QEMU_OPT_STRING,
 235             .help = "URL to the NFS file",
 236         },
 237         { /* end of list */ }
 238     },
 239 };
 240
 241 static void nfs_detach_aio_context(BlockDriverState *bs)
 242 {
 243     NFSClient *client = bs->opaque;
 244
 245     aio_set_fd_handler(client->aio_context,
 246                        nfs_get_fd(client->context),
 247                        NULL, NULL, NULL);
 248     client->events = 0;
 249 }
 250
 251 static void nfs_attach_aio_context(BlockDriverState *bs,
 252                                    AioContext *new_context)
 253 {
 254     NFSClient *client = bs->opaque;
 255
 256     client->aio_context = new_context;
 257     nfs_set_events(client);
 258 }
 259
 260 static void nfs_client_close(NFSClient *client)
 261 {
 262     if (client->context) {
 263         if (client->fh) {
 264             nfs_close(client->context, client->fh);
 265         }
 266         aio_set_fd_handler(client->aio_context,
 267                            nfs_get_fd(client->context),
 268                            NULL, NULL, NULL);
 269         nfs_destroy_context(client->context);
 270     }
 271     memset(client, 0, sizeof(NFSClient));
 272 }
 273
 274 static void nfs_file_close(BlockDriverState *bs)
 275 {
 276     NFSClient *client = bs->opaque;
 277     nfs_client_close(client);
 278 }
 279
 280 static int64_t nfs_client_open(NFSClient *client, const char *filename,
 281                                int flags, Error **errp)
 282 {
 283     int ret = -EINVAL, i;
 284     struct stat st;
 285     URI *uri;
 286     QueryParams *qp = NULL;
 287     char *file = NULL, *strp = NULL;
 288
 289     uri = uri_parse(filename);
 290     if (!uri) {
 291         error_setg(errp, "Invalid URL specified");
 292         goto fail;
 293     }
 294     if (!uri->server) {
 295         error_setg(errp, "Invalid URL specified");
 296         goto fail;
 297     }
 298     strp = strrchr(uri->path, '/');
 299     if (strp == NULL) {
 300         error_setg(errp, "Invalid URL specified");
 301         goto fail;
 302     }
 303     file = g_strdup(strp);
 304     *strp = 0;
 305
 306     client->context = nfs_init_context();
 307     if (client->context == NULL) {
 308         error_setg(errp, "Failed to init NFS context");
 309         goto fail;
 310     }
 311
 312     qp = query_params_parse(uri->query);
 313     for (i = 0; i < qp->n; i++) {
 314         unsigned long long val;
 315         if (!qp->p[i].value) {
 316             error_setg(errp, "Value for NFS parameter expected: %s",
 317                        qp->p[i].name);
 318             goto fail;
 319         }
 320         if (parse_uint_full(qp->p[i].value, &val, 0)) {
 321             error_setg(errp, "Illegal value for NFS parameter: %s",
 322                        qp->p[i].name);
 323             goto fail;
 324         }
 325         if (!strcmp(qp->p[i].name, "uid")) {
 326             nfs_set_uid(client->context, val);
 327         } else if (!strcmp(qp->p[i].name, "gid")) {
 328             nfs_set_gid(client->context, val);
 329         } else if (!strcmp(qp->p[i].name, "tcp-syncnt")) {
 330             nfs_set_tcp_syncnt(client->context, val);
 331 #ifdef LIBNFS_FEATURE_READAHEAD
 332         } else if (!strcmp(qp->p[i].name, "readahead")) {
 333             if (val > QEMU_NFS_MAX_READAHEAD_SIZE) {
 334                 error_report("NFS Warning: Truncating NFS readahead"
 335                              " size to %d", QEMU_NFS_MAX_READAHEAD_SIZE);
 336                 val = QEMU_NFS_MAX_READAHEAD_SIZE;
 337             }
 338             nfs_set_readahead(client->context, val);
 339 #endif
 340         } else {
 341             error_setg(errp, "Unknown NFS parameter name: %s",
 342                        qp->p[i].name);
 343             goto fail;
 344         }
 345     }
 346
 347     ret = nfs_mount(client->context, uri->server, uri->path);
 348     if (ret < 0) {
 349         error_setg(errp, "Failed to mount nfs share: %s",
 350                    nfs_get_error(client->context));
 351         goto fail;
 352     }
 353
 354     if (flags & O_CREAT) {
 355         ret = nfs_creat(client->context, file, 0600, &client->fh);
 356         if (ret < 0) {
 357             error_setg(errp, "Failed to create file: %s",
 358                        nfs_get_error(client->context));
 359             goto fail;
 360         }
 361     } else {
 362         ret = nfs_open(client->context, file, flags, &client->fh);
 363         if (ret < 0) {
 364             error_setg(errp, "Failed to open file : %s",
 365                        nfs_get_error(client->context));
 366             goto fail;
 367         }
 368     }
 369
 370     ret = nfs_fstat(client->context, client->fh, &st);
 371     if (ret < 0) {
 372         error_setg(errp, "Failed to fstat file: %s",
 373                    nfs_get_error(client->context));
 374         goto fail;
 375     }
 376
 377     ret = DIV_ROUND_UP(st.st_size, BDRV_SECTOR_SIZE);
 378     client->st_blocks = st.st_blocks;
 379     client->has_zero_init = S_ISREG(st.st_mode);
 380     goto out;
 381 fail:
 382     nfs_client_close(client);
 383 out:
 384     if (qp) {
 385         query_params_free(qp);
 386     }
 387     uri_free(uri);
 388     g_free(file);
 389     return ret;
 390 }
 391
 392 static int nfs_file_open(BlockDriverState *bs, QDict *options, int flags,
 393                          Error **errp) {
 394     NFSClient *client = bs->opaque;
 395     int64_t ret;
 396     QemuOpts *opts;
 397     Error *local_err = NULL;
 398
 399     client->aio_context = bdrv_get_aio_context(bs);
 400
 401     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
 402     qemu_opts_absorb_qdict(opts, options, &local_err);
 403     if (local_err) {
 404         error_propagate(errp, local_err);
 405         ret = -EINVAL;
 406         goto out;
 407     }
 408     ret = nfs_client_open(client, qemu_opt_get(opts, "filename"),
 409                           (flags & BDRV_O_RDWR) ? O_RDWR : O_RDONLY,
 410                           errp);
 411     if (ret < 0) {
 412         goto out;
 413     }
 414     bs->total_sectors = ret;
 415     ret = 0;
 416 out:
 417     qemu_opts_del(opts);
 418     return ret;
 419 }
 420
 421 static QemuOptsList nfs_create_opts = {
 422     .name = "nfs-create-opts",
 423     .head = QTAILQ_HEAD_INITIALIZER(nfs_create_opts.head),
 424     .desc = {
 425         {
 426             .name = BLOCK_OPT_SIZE,
 427             .type = QEMU_OPT_SIZE,
 428             .help = "Virtual disk size"
 429         },
 430         { /* end of list */ }
 431     }
 432 };
 433
 434 static int nfs_file_create(const char *url, QemuOpts *opts, Error **errp)
 435 {
 436     int ret = 0;
 437     int64_t total_size = 0;
 438     NFSClient *client = g_new0(NFSClient, 1);
 439
 440     client->aio_context = qemu_get_aio_context();
 441
 442     /* Read out options */
 443     total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
 444                           BDRV_SECTOR_SIZE);
 445
 446     ret = nfs_client_open(client, url, O_CREAT, errp);
 447     if (ret < 0) {
 448         goto out;
 449     }
 450     ret = nfs_ftruncate(client->context, client->fh, total_size);
 451     nfs_client_close(client);
 452 out:
 453     g_free(client);
 454     return ret;
 455 }
 456
 457 static int nfs_has_zero_init(BlockDriverState *bs)
 458 {
 459     NFSClient *client = bs->opaque;
 460     return client->has_zero_init;
 461 }
 462
 463 static int64_t nfs_get_allocated_file_size(BlockDriverState *bs)
 464 {
 465     NFSClient *client = bs->opaque;
 466     NFSRPC task = {0};
 467     struct stat st;
 468
 469     if (bdrv_is_read_only(bs) &&
 470         !(bs->open_flags & BDRV_O_NOCACHE)) {
 471         return client->st_blocks * 512;
 472     }
 473
 474     task.st = &st;
 475     if (nfs_fstat_async(client->context, client->fh, nfs_co_generic_cb,
 476                         &task) != 0) {
 477         return -ENOMEM;
 478     }
 479
 480     while (!task.complete) {
 481         nfs_set_events(client);
 482         aio_poll(client->aio_context, true);
 483     }
 484
 485     return (task.ret < 0 ? task.ret : st.st_blocks * 512);
 486 }
 487
 488 static int nfs_file_truncate(BlockDriverState *bs, int64_t offset)
 489 {
 490     NFSClient *client = bs->opaque;
 491     return nfs_ftruncate(client->context, client->fh, offset);
 492 }
 493
 494 /* Note that this will not re-establish a connection with the NFS server
 495  * - it is effectively a NOP.  */
 496 static int nfs_reopen_prepare(BDRVReopenState *state,
 497                               BlockReopenQueue *queue, Error **errp)
 498 {
 499     NFSClient *client = state->bs->opaque;
 500     struct stat st;
 501     int ret = 0;
 502
 503     if (state->flags & BDRV_O_RDWR && bdrv_is_read_only(state->bs)) {
 504         error_setg(errp, "Cannot open a read-only mount as read-write");
 505         return -EACCES;
 506     }
 507
 508     /* Update cache for read-only reopens */
 509     if (!(state->flags & BDRV_O_RDWR)) {
 510         ret = nfs_fstat(client->context, client->fh, &st);
 511         if (ret < 0) {
 512             error_setg(errp, "Failed to fstat file: %s",
 513                        nfs_get_error(client->context));
 514             return ret;
 515         }
 516         client->st_blocks = st.st_blocks;
 517     }
 518
 519     return 0;
 520 }
 521
 522 static BlockDriver bdrv_nfs = {
 523     .format_name                    = "nfs",
 524     .protocol_name                  = "nfs",
 525
 526     .instance_size                  = sizeof(NFSClient),
 527     .bdrv_needs_filename            = true,
 528     .create_opts                    = &nfs_create_opts,
 529
 530     .bdrv_has_zero_init             = nfs_has_zero_init,
 531     .bdrv_get_allocated_file_size   = nfs_get_allocated_file_size,
 532     .bdrv_truncate                  = nfs_file_truncate,
 533
 534     .bdrv_file_open                 = nfs_file_open,
 535     .bdrv_close                     = nfs_file_close,
 536     .bdrv_create                    = nfs_file_create,
 537     .bdrv_reopen_prepare            = nfs_reopen_prepare,
 538
 539     .bdrv_co_readv                  = nfs_co_readv,
 540     .bdrv_co_writev                 = nfs_co_writev,
 541     .bdrv_co_flush_to_disk          = nfs_co_flush,
 542
 543     .bdrv_detach_aio_context        = nfs_detach_aio_context,
 544     .bdrv_attach_aio_context        = nfs_attach_aio_context,
 545 };
 546
 547 static void nfs_block_init(void)
 548 {
 549     bdrv_register(&bdrv_nfs);
 550 }
 551
 552 block_init(nfs_block_init);